Dual Clutch Shift Control for Hybrid Vehicle Drivability
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Solution Overview
Problem
Existing shift control methods for automatic transmissions in vehicles are inefficient in synchronizing input and output shaft speeds, leading to prolonged shift times and variable shift quality, particularly in hybrid vehicles that lack a torque converter, affecting drivability and fuel efficiency.
Innovation Solution
A shift control apparatus and method that utilizes a dual clutch transmission system, where a vehicle controller synchronizes input and output shaft speeds by controlling torque source speed, maintaining transfer torque through clutch management and speed control, and generating target speed profiles to ensure smooth shifts and prevent power interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If manual synchronization using slip of friction elements is used, then the shift control can be performed, but the shift time becomes long and shift quality changes with driving state
Solution Approach 1:
The patent replaces the traditional mechanical slip-based synchronization method with an active control system that uses a controller to manage friction element engagement. The controller precisely controls the engagement timing and pressure of friction elements (first and second friction elements) to synchronize shaft speeds, eliminating reliance on passive mechanical slip characteristics. This substitution enables consistent shift quality across different driving conditions while reducing shift time through optimized engagement control.
Solution Approach 2:
The patent implements a feedback control mechanism where the controller monitors the rotational speeds of the input shaft and output shaft, and adjusts the engagement control of friction elements based on the speed difference. The controller continuously compares actual speeds with target speeds and modifies friction element engagement pressure and timing accordingly, ensuring accurate synchronization. This feedback loop maintains reliable shift quality regardless of varying driving states such as load or slope conditions.
2Loss of energy
If hybrid vehicle does not use torque converter for fuel efficiency improvement, then fuel efficiency is improved, but drivability is adversely affected when shift quality is not good
Solution Approach 1:
The patent replaces the traditional torque converter-based smooth transition mechanism with an active electronic control system that manages friction element engagement. The controller precisely regulates the engagement timing and pressure of the first and second friction elements during shift operations, replicating and improving upon the smooth torque transfer previously achieved by torque converters. This substitution maintains fuel efficiency by eliminating the torque converter while enhancing drivability through precise electronic control of the friction elements, ensuring consistent shift quality across all driving conditions.
3Device complexity
If traditional shift control method is used, then the system structure is simple, but shift quality changes in response to driving state such as slope and vehicle load
Solution Approach 1:
The patent implements a universal control system that handles multiple shifting scenarios and driving conditions through a single integrated controller. The controller manages the engagement of both the first friction element (for downshifts) and the second friction element (for upshifts), adapting its control strategy based on the specific driving state such as slope, load, or acceleration requirements. This multi-functional control approach ensures consistent shift quality across all operating conditions without requiring separate mechanical mechanisms for different driving states, maintaining system simplicity while achieving reliability.
Data Source
AI summary
The present disclosure relates to a shift control apparatus of a vehicle and its method. In particular, the shift control apparatus includes: a transmission including a first clutch and a second clutch; a torque source to generate power for driving a vehicle; a data detector to detect a vehicle state data; and a vehicle controller to connect a current stage synchronizer to a next stage driving gear if the vehicle state data satisfy a shift condition, release the first clutch to be connected to the driving gear of a current stage, perform a speed control of a torque source while maintaining the second clutch connected to the driving gear of the next stage in a slip state, and release the second clutch and connect the first clutch if the vehicle stage data satisfy a speed control completion condition to complete a shift to a target stage.